Comment 11 for bug 515915

Creating the /var/lib/samba/usershares directory seems to have solved this issue for me. I tried this after discovering this line in the ~/.xsession-errors file:

** (gnome-settings-daemon:4650): WARNING **: Could not acquire name
Nautilus-Share-Message: Called "net usershare info" but it failed: 'net usershare' returned error 255: net usershare: cannot open usershare directory /var/lib/samba/usershares. Error No such file or directory
Please ask your system administrator to enable user sharing.

No more hangs from opening PDFs from Nautilus or from within Evince. Oddly enough, it still hangs when opening a PDF that's already opened.